Molding composition and method of making



Patented May 27, 194-1 MOLDING C(P-MPO SITION AND lWIETHOD, OF MAKING Robert P. Gutterman, Brookline, Mass.

No Drawing. Application July P2, 1938, Serial No. 2417,6553

17 Claims.

This invention relates to a molding composition and to a method ofmaking and shaping the same.

The present invention provides a method of converting waste leather material, such as leather scrap or dust, into a valuable molding compound or composition, which is suitable for commercial use in the manufacture of molded objects of various kinds. Such leather waste may contain the various tanning, filling or other agents which are customarily added to leather in the course of the tanning and finishing operations or may be substantially free from such extraneousmaterials and consist practically exclusively of hide or leather substance, per se.

It is found, by the present invention, that leather may be given a preliminary treatment which converts it to a form-or condition in which it is quite different from the initial material. This product constitutes an intermediate organic compound which is further characterized by being capable of undergoing reaction to produce a solidified product, which is in turn capable of reacting, under heat and pressure, to become integrated and develop strength and hardness to a high degree.

A preliminary step, which is desirable generally and necessary with scrap leathers which contain appreciable matter other than leather substance, consists in leaching or soaking the leather in phenolic solution, preferably at elevated temperatures up to the boiling point. This is effective to dissolve such materials, which are the-n removed by decanting the supernatant liquor. The leather scrap is next digestedwith a mineral acid, and heated. In this treatment, a wide range of conditions may be provided, as represented, for example, by an aqueous solution of hydrochloric acid solution, which may vary from .01 to normal, in concentration. Upon such treatment, the leather is converted from a solid fibrous condition-whether in the form of dust, shreds, or scrapsto a thick, viscous fluid, which eventually becomes a homogeneous liquid, giving no evidence of its original solid, fibrous structure. It separates from the aqueous solution of acid by which it was converted, and may be further separated from entrained solution by mechanically working the mass. It itself remains liquid, however, Which is its characteristic condition, and accordingly may be freely mixed with and reacted upon by the formaldehyde solution (or other aldehyde, such as paraldehyde or acetaldehyde) which is next added and incorporated therewith. The mixing action is continued, with heat, whereupon the mass hardens to a firm, solid, consistency which permits it to be granulated or pulverized to powder form. This is capable of being molded, and under pressure and heat short of carbonizing the product (e. g., 1,000 to 8,000 lbs. per sq. inch and 50 C. to 300 C.) it

becomes partially to completely thermoplastic and not only conforms accurately to the contours and surfaces of the molding chamber, but also solidifies andhardens to a dense, rigid bodyto form the finished article desired.

In a typical instance of carrying out the invention in actual practice, the procedure may be conducted as follows: 7

Scrap leather is cutup or otherwise reduced to convenient size for handling (e. g., pieces 3% to ,4; inch in thicknessand a matter of l to 25 square inches in surface area) and mixed in the proportions of gramsof leather 300 c. c. of water and 10 c. c, of a saturated water solution of phenol and boiled for 10 minutes. Then 50 c. c. of a6N hydrochloric acid solution is added and the mixture again boiledfor25 minutes.

At this stage, and for this period of boiling, the leather acquired a completely and uniformly amorphous condition. I short of 25 minutes, or for example, after 15 minutes of boiling, the leather would be only partially converted to a liquid condition, leaving a part of the fibers unchanged, which will then serve as fibrous filler.

The mixture is thencooled to 30? C to 40 0,, at which point the mixture settles and the converted leather, which is a thick, viscous fluid, separates from the aqueous fraction. The converted leather is sufficiently viscous so that itmay be collected and lifted out of the waterbyhand. It is then kneaded, either by hand or mechanically, so as to express the water which may be retainedby it. This may be done on rollers, by squeezing and compressingthe mass, or by repeatedly stretching it out, since it is plastic, or like kneading operations. The converted mass is then heatedto a more freely fluid condition at which it will flow readily, and formaldehyde added in the proportions of 6 c. c. of a 40% aqueous formaldehyde solution. This is thoroughly stirred into the mixture, to distribute it uniformly therethrough and the mass is allowed toharden and age for 48 hours.

The mass is then pulverized, preferably by impact asin a ball mill, to such degree of fineness as is desired or required by the molding operation intended. The powder is filled into the mold and heated to a temperature of 100 C. and subjected to a molding pressure of 4,000 pounds per square inch, and held at this temperature and pressure for 8 minutes. The powder thereupon melts and flows to correspond accurately to the mold surfaces, acquiring a polish or other specific characteristic thereof, as well as the shape, size and contour provided therein. The molded'object may then be withdrawn freely-or, if necessary, may be allowed to stay longer in the mold and to cool, to develop further stiffness or rigidity for convenient removal.

If boiling were arrested 7 'The molded product is susceptible to further hardening, with age, after withdrawing from the mold, but small pieces are effectively developed in two days time, and are suitable for most purposes.

While traces of phenol which may be left in the charge from the preliminary treatment of the leather scrap will be free to undergo polymerization and condensation with the formaldehyde this is merely incidental,-fo-r the liquefied leather product is itself condensed or polymerized by the formaldehyde to solid form. However, when phenol is used upon the leather in the preliminary treatment as above described, it appears to act as a solvent of the acid converted leather substance and to promote its fluid condition and to prolong this condition even after the addition of the formaldehyde. If the preliminary treatment with phenol were to be omitted, the fluid, intermediate conversion product of the acid treated leather would be more rapidly reacted upon by the formaldehyde and hence exhibit a more rapidly setting action in the final stages and molding of the composition. It is clear therefore that the principal or entire conversion of the charge relates to the leather substance and that this forms a new intermediate reaction product which is capable of undergoing reaction with formaldehyde to produce a molding powder and that this in turn is susceptible of further molding and hardening under heat and pressure to form a homogeneous, integrated mass of uniform, hard, resilient consistency of substantially any shape required.

I claim:

1. Method of making moldable compositions, comprising the steps of treating leather waste with a water solution of phenol, then separating the leather therefrom, heating the leather waste with an inorganic acid solution until the leather becomes fluid, removing it from the acid solution, heating with an aldehyde, and, upon solidification and drying, pulverizing the mass to powder form.

2. Method of making moldable compositions, comprising the steps of treating leather waste with a water solution of phenol, then separating the leather therefrom, heating the leather waste with an inorganic acid solution untila substantial proportion of the leather becomes fluid, removing it from the acid solution, heating with an aldehyde, and, upon solidification and drying, pulverizing the mass to powder form.

3. Method of making moldable compositions, comprising the steps of treating leather waste with a water solution of phenol, then separating the leather therefrom, heating with a hydrochloric acid solution of from .01 to normal until the leather becomes fluid, removing it from the acid solution, mixing with formaldehyde, and, upon solidification and drying, pulverizing th mass to powder form.

4. Method of making moldable compositions, comprising the steps of treating leather Waste with a water solution of phenol, then separating the leather therefrom, heating with an inorganic acid solution until the leather becomes fluid, removing it from the acid solution, kneading the mass to express and remove the liquor associated therewith, mixing with an aldehyde, and, upon solidification and drying, pulverizing the mass to powder form. a

5. An intermediate product, suitable for reaction with an aldehyde to produce a thermoplastic molding composition, comprising the fluid reaction product of leather, phenol, and a mineral acid. 1

6. An intermediate product, suitable for reaction with formaldehyde to produce a thermoplastic molding composition, comprising the fluid reaction product of leather, phenol, and hydrochloric acid.

'7. A thermoplastic composition comprising the fluid reaction product of leather, phenol, and a mineral acid.

8. A thermoplastic composition comprising the reaction product of an aldehyde and the fluid reaction product of leather, phenol, and a mineral acid.

9. A thermoplastic composition comprising the reaction product of formaldehyde and the fluid reaction product of leather, phenol, and hydrochloric acid.

10. A shaped object or article composed substantially of the reaction product of an aldehyde and the fluid reaction product of leather, phenol, and a mineral acid.

1 1. A shaped object or article composed substantially of the reaction product of formaldehyde and the fluid reaction product of leather, phenol, and hydrochloric acid.

12. Method of making moldable compositions, comprising the steps of treating leather waste, containing tanning, filling or finishing agents, with a water solution of phenol, then separating the leather therefrom, heating the leather waste with an inorganic acid solution until the leather becomes fluid, removing it from the acid solution, heating with an aldehyde, and upon solidification and drying, pulverizing the mass to powder form.

13. Method of making moldable compositions, comprising the steps of treating leather waste, containing tanning, filling or finishing agents, with a water solution of phenol, then separating the leather therefrom, heating the leather waste with an inorganic acid solution until a substantial proportion of the leather becomes fluid, removing it from the acid solution, heating with an aldehyde, and upon solidification and drying, pulverizing the mass to powder form. v

14. Method of making moldable compositions, comprising the steps of treating leather waste, containing tanning, filling or finishing agents, with a water solution of phenol, then separating the leather therefrom, heating the leather waste with an inorganic acid solution until the leather becomes fluid, removing it from the acid solution, kneading the mass to express and remove the liquor associated therewith, heating with an aldehyde, and upon solidification and drying, pulveriz-ing the mass to powder form.

15. An intermediate product, suitable for reaction with an aldehyde to produce a thermoplastic molding composition, comprising the fluid reaotion product of leather, containing tanning, filling or finishing agents, with phenol and a mineral acid.

16. A thermoplastic composition comprising the fluid reaction product of leather containing tanning, filling or finishing agents, with an aldehyde, phenol and a mineral acid.

1 7. A shaped object or article composed substantially of the reaction product of an aldehyde and the fluid reaction product of leather, containing tanning, filling or finishing agents, phenol,

and a mineral acid.

ROBERT P. 

